Motor



June 3, 1941lr` A A, MANN 2,243,878

MOTOR Filed Aug. 31, 1958 72 ze 32 /1 A'. MART/N @mam ` @ormay PatentedJune 3, 1941 UNITED STATES PATENT OFFICE MOTOR Angus A. Martin, Winsted,Conn. Application August 31, 1938, Serial No. 227,757

11 Claims.

This invention relates to hair clipping and shaving instruments and moreparticularly to a motor designed and constructed in a manner especiallyadapting it to use therewith. Such instruments commonly have theoperating motor mounted Within the handle of the instrument and oneobject of my invention is the production of a very compact and eilicientmotor for this purpose, and more .particularly a motor of the make andbreak type which will operate on both D. C. and A. C. current.

Electric motors have heretofore been commonly constructed with ythefield magnets located laterally outside of the rotor or armature andsuch construction requires a Very substantial width space within thehandle in which the motor is mount-ed. In accordance with my invention,I propose to mount the rotor in longitudinal al-ignment with the fieldand the poles thereof in end to end relation with the eld poles, therotor being mounted to rotate on an axis extending longitudinally ofIthe combined rotor and field and located midway between the poles. Sucharrangement greatly reduces the Width of mounting space heretoforerequired and provides a streamlined motor adapted to t within a handleof like design.

I have found that the strongest pull of a magnet is at its extreme ends,whereby the greatest pulling power is produced by arranging the armatureand field poles in end to end relation, but I have also found that sucharrangement produces a substantial drag effect on the armature after itspoles leave their most effective position relative to the eld poles. Themagnetic action causing this drag effect appears to take place largely'at the inner or shorter radius portions of the poles due to the factthat, the rotary speed or distance traveled `by such portions being lessthan that of the outer portions, the inner portions of the poles remainin close relationship and form a metallic bridge between the poles afterthe outer portions thereof have become separated. A further andimportant feature of my invention resides in so constructing the polesas substantially to eliminate this drag, whereby retaining the greaterpulling power of the poles in the forward direction while Wholly orlargely eliminating the opposing magnetic drag, all as hereinafter morespecifically described. Such improvement results not only in a morepowerful motor but also in a motor having very substantially greaterspeeds and one in which lheating of the field coil is greatly reduced.

As above stated, the streamlined construction of my improved motorparticularly adapts it to use in a handle casing for clipping-shavinginstruments and the like, and a further feature of the invention residesin sealing the motor Within t-he casing against the ingress of water andalso in providing a relatively small closed chamber within the casingfor housing the make and break contacts. Since the instru-ment employingthe motor may be used around or with water, the sealing of the motoreliminates motor trouble which might otherwise occur due to moisture,and the housing of the make and break contacts prevents burning of thecontacts by eliminating oxygen from the chamber. The production of suchan improved and compact motor combination having the parts mounted andoperating in a most efcient manner, all as hereinafter more specificallydescribed, comprises a further object of the invention.

These and other features of the invention will be best understood andappreciated from the following description of a preferred embodimentthereof selected for purposes of illustration and shown in theaccompanying drawing, in which Fig. 1 is a. partial side elevation of aclipping instrument employing my improved motor,

Fig. 2 is a front elevation thereof with the cover removed,

Fig. 3 is a longitudinal sectional view taken on line 3-3 of Fig. 2,

Fig. 4 is a view taken on line 4-4 of Fig. 2 and showing the instrumentin front end elevation,

Fig. 5 is a sectional view taken on line 5 5 of Fig. 2,

Fig. 6 is a sectional view taken on line 6-6 of Fig. 2 but showing thearmature rotated 90,

Fig. 7 is a fragmentary view of a detail.

Referring specifically to the drawing by reference characters, I0 and I2indicate respectively the body and cover of a handle casing for aclipping instrument of the nature shown in my copending application,Serial No. 134,823, filed April 3, 1937, the cover being held to thebody I0 by screws I4. The subject matter herein claimed relates to themotor and handle details which are not disclosed or claimed in saidcopending application. A clipping head l5 is mounted on the forward endof the handle and its clipping blade l 6 is adapted to be reciprocatingby a crank |18 on the forward end of a motor shaft v2l). This shaftextend-s through a solid end portion 2| of the body l0 and its rear endrests on a thrust ball bearing 22 in a wall 23 integral with the casing.Oil may be supplied to this bearing through a hole drilled through ascrew 24.

The motor compris-es a laminated U-shaped field magnet 25 having anenergizing coil 26 associated therewith between the two poles 28terminating in end portions, bolts 29 serving to secure the magnet tothe casing. Fixed to the shaft 2l) by a screw 3f! is a U-shaped unwoundarmature 3l having two poles 32 terminating in end portions and opposingthe poles 28 of the magnet in end to end relation, the armature andshaft being held against longitudinal forwardY movement by spacingwashers 34.

The motor illustrated is of the make andbreak type and one feature ofthe invention resides in housing'the make and break contacts within asubstantially airtight chamber whereby eliminating lburning effect `onthe contacts, Such a chamber 36 is provided within the portion 2l of thecasing and is covered by a sheet metal strip 31 secured by screws 38.One contact 40 is Xed and the other contact 4l is carried on a member l2of insulation material pivoted at 44. A metal pin 45 extends through themember l2 and secures the movable contact plate to a plate 46 andprovides an electrical connection therebetween. The member is normallypivoted in the contact closing direction by a spring 48 engaging theplate 46, this spring also serving as a part of the electric circuit.The spring normally holds the pivoted member in contact with a cam 5i)formed on the shaft 20. The contact members are supported on a plate 5Iheld in place in the bottom of the chamber 36 by a screw 52, the fixedcontact being held by a bolt 54. Terminals 55 and 56 from the contactseXtend outwardly through the wall of the chamber and are sealed airtighttherein.

A relatively long cord supporting tube 58 is fixed water tight withinthe rear end of the casing and the electric cord G extends therethroughto posts 62. A cable 64 connects one post 62 with the terminal 55. Acable 86 connects the other post 2 with one end of the coil 25, andanother cable 68 connects the other end of the coil to the terminal E.

It will be apparent that the mounting of the armature and field magnetin end to end relation provides a streamlined motor of relatively narrowwidth adapted to t within a handle of like design. This end to endrelation produces maximum pulling power on the armature which wouldnormally also result in producing a substantial drag thereon after itspoles leave their most effective position relative to the field poles.The magnetic action causing this drag effect appears to take placelargely at the inner or shorter radius portions of the poles due to thefact that, the rotary speed or distance traveled by such portions beingless than that of the outer portions, the inner portions of the polesremain in close relationship after the outer portions thereof havebecome separated.

In accordance with my invention, I substantially reduce or eliminatethis drag by beveling the end portions of the poles, as illustrated atl0, in a direction converging toward the free ends thereof and radiallyinward toward the shaft 20. The beveling is preferably such that, uponrotation of the armature, the armature poles leave the field polessubstantially at the same time along the relatively receding side edgesof such poles, i, e., these edges are substantially parallel in suchrelative position of the poles. As thus constructed the pulling magneticeffect in the forward direction is retained and even increased while theopposing magnetic drag on the armature is wholly or largely eliminated.

This effect may best be understood by reference to Fig. 6 wherein therelation of the field and armature poles 28 and 32 are shown in endview, and also to Fig. 7. It will be appreciated that two cooperatingmagnets are most effective when they have relatively large parallelsurfaces presented to each other and by beveling olf the inner cornersof the poles as illustrated, such parallel surfaces are provided on thearmature and field poles, the cooperating edges 12 of the poles beingsubstantially parallel as the poles 32 approach or recede from the poles28. Such construction provides maximum pulling power on the armaturewhen the edges 12 approach each other to the most effective pullingposition and, furthermore, the cutting or beveling off of the corners ofthe poles eliminates the drag which would be effective on the armatureif such coiners were allowed to remain and form a metallic bridgebetween the poles during a substantial part of the rotation of thearmature as the armature poles recede from the eld poles. The greaterefficiency produced by this improvement results not only in a morepowerful motor but also in a motor having very substantially greaterspeeds and one in which heating of the field coil is greatly reduced.

The instrument illustrated as employing my improved motor may be usedfor dry clipping or shaving and may also be used with lather or moistshaving. In either case, the instrument may be subjected to waterimmersion and a further feature of the invention resides in theprovision of a construction preventing the ingress of moisture to themotor. To this end, a watertight gasket 'I4 is mounted on the shaft 20beneath the starting disk l5, and water-tight gaskets 'i6 and 'Il areprovided between the cover I0 and body I2 along their cooperating edges.Such gaskets, together with the water-tight joint between the tube 58and the casing, serve effectively to prevent moisture from penetratinginto the motor casing.

It will now be apparent that I have produced and herein disclosed asuperior product of the nature illustrated and described, and what Iclaim as new and desire to secure by United States Letters Patent is:

1. An electric motor comprising a field magnet having a plurality ofrelatively spaced poles extending outwardly therefrom and terminating inend portions, an energizing coil associated with the magnet, an armaturehaving a pluralityof relatively spaced poles terminating in end p0rtionsopposed to and arranged to cooperate with the end portions of the -fieldpoles in end to end relation, the armature being mounted to rotate on anaxis located equal distances from the field poles and equal distancesfrom the armature poles and extending longitudinally of the poles, andmake and break contacts in the coil circuit under control of thearmature rotation, the cooperating end portions of the poles beingshaped to leave a substantially uniform spacing between the end portionsof the armature poles and the cooperating end portions of the fieldpoles along their side edges as the former approach and recede from thelatter upon rotation of the armature.

2. The motor defined in claim 1 in which the magnetic material in thecooperating end portions of the poles gradually increases at the sidesthereof from the free ends of the poles rearwardly.

3. The motor defined in claim l in which the magnetic material in thecooperating end portions of the poles gradually increases at the sidesthereof from the free ends of the poles rearwardly and from the radiallyinward faces thereof outwardly.

4. The motor defined in claim 1 in which the sides of the end portionsof the poles are bevelled in a direction converging toward the free endsthereof.

5. The motor defined in claim 1 in which the sides of the end portionsof the poles are bevelled in a direction converging toward the free endsthereof and radially inward toward said axis.

6. An electric motor comprising a laminated U-shaped field magnet havingthe legs thereof forming two oppositely disposed poles extendingoutwardly therefrom, an energizing coil associated with the magnetbetween the poles, a U- shaped unwound armature having the legs thereofforming two oppositely disposed poles opposed to and arranged tocooperate with the field poles in end to end relation, the armaturebeing mounted to rotate on an axis located midway between the poles andextending longitudinally of the poles, and make and break contacts inthe coil circuit under control of the armature rotation.

7. The motor defined in claim 6 in which the poles are all equallyspaced from said axis and in which the side portions of the poles arebevelled in a direction converging toward the free ends thereof.

8. An electric motor comprising a field coil, a U-shaped field magnethaving the intermediate body portion thereof associated with the coiland having the legs thereof projecting outwardly beyond the coil inparallel and spaced relation and providing two poles, a U-shaped unwoundarmature mounted to rotate on an axis extending between andlongitudinally of the poles and having the legs thereof providing twopoles extending toward the magnet to a position wherein their endsclosely face the ends of the field Poles when the armature is rotated toa position in the plane of the magnet, and make and break contacts inthe coil circuit under control of the armature rotation.

9. An electric motor comprising an electromagnetic fleld, a rotaryarmature cooperating therewith, a casing enclosing the field andarmature, make and break contacts in the field circuit, means enclosingthe contacts within a relatively small and substantially air tightchamber within the casing, and means including a shaft driven by thearmature and extending through the chamber for operating the contacts.

10. An electric motor comprising an electromagnetic field, a rotaryarmature cooperating therewith, a fixed contact and a cooperatingmovable contact in the eld circuit, a pivoted member carrying themovable contact, a spring acting against the pivoted member in adirection to close the contacts and serving as a portion of saidcircuit, and means including a shaft driven by the armature forintermittently pivoting said member against the action of the spring.

11. In a device of the class described, a casing having a solid forwardend portion and a chamber rearwardly thereof, a motor including anelectro-magnetic field magnet and a cooperating armature in the chamber,a shaft rotatably supporting the armature and extending forwardlythrough said end portion, means preventing leakage into the chamberalong the shaft, a cover on the casing enclosing the chamber, a gasketbetween the casing and cover preventing leakage into the chamber, makeand break contacts in the field circuit under control of the armaturerotation, and means providing a relatively small closed chamber in thecasing between said solid end portion of the casing and the first namedchamber, said contacts being within said closed chamber.

ANGUS A. MARTIN.

